Saturable reactor apparatus



Nov. 4, 1952 H M, OGLE 2,617,090l

SATURABLE REAcToR APPARATUS Filed June 17, 195o 2 SHEETS- SHEET 1 Inventor; H ugh M. Ogle,

Nov. 4, 1952 H. M. OGLE 2,617,090

SATURABLE REACTOR APPARATUS Filed June 17, 1950 2 SHEETS-SHEET 2 Fig. 5.

Fig.

A-C- SUPPLY Ihveto'. Hugh M. og,

.by w 2% His Attorney.

Patented Nov. 4, 1952 SATURABLE REACTOR APPARATUS Hugh M. Ogle, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application June 17, 1950, Serial No. 168,679

6 Claims.

My invention relates to electrical induction apparatus and, more particularly, to apparatus employing saturable core reactors for controlling the reactance of an alternating current circuit.

Saturable core reactors having a plurality of alternating current reactance windings and one or more magnetic saturation control windings are now used extensively as the electric current controlling elements in suitable alternating current circuits. Many such saturable reactor circuits perform a current or voltage amplifying function and have become known as magnetic amplifiers.

One popular type of saturable reactor control circuits, commonly referred to as push-pull magnetic ampliiiers, employ one or two saturable reactors having, in total, four alternating current reactance windings and one or more control windings for varying the level of magnitization in the cores in accordance with an external electric signal. In such push-pull magnetic amplifiers, suitable current rectifying means are included in circuit relation with the reactance windings and a load device such that a respective two of the four reactance windings conduct current during source voltage alternations of one polarity, and the other two reactance windings are conductive during source voltage alternations of opposite polarity. The load device may appropriately be connected to be energized by either the sum or the difference of the prevailing currents.

It has heretofore been the usual practice to employ a pair of saturable reactors each having three-legged cores for such push-pull magnetic amplifier circuits; the reactance windings being wound on respective outer legs and the Control windings being wound on the central leg ofeach core. In an arrangement of this type, there is, of course, no magnetic interaction of the flux in one reactor upon that of the other reactor, and the separate control windings of each reactor must be interconnected to respond to the same external signal.

Accordingly, an object of my present invention is to provide new and improved saturable reactor apparatus suitable for use with alternating current circuits employing a plurality of reactance windings, and particularly adapted for use with push-pull magnetic amplier circuits.

An additional object of my invention is to provide a new and improved structural arrangement for a saturable reactor whereby two or more three-legged saturable reactor cores may be combined into a unified core structure such that improved performance may be derived from the magnetic iiux interaction of the normally separate cores.

Another object of my invention is to provide a saturable reactor core structure whereby current owing through an even plurality of at least four reactance windings of a reactor may be simultaneously and symmetrically controlled by a single saturation control winding without resorting to the expedient of multiple-layer windings.

A further object of my invention is to provide a saturahle reactor apparatus for push-pull magnetic amplier circuits in which a convenient location is provided for current rectifying elements associated with the saturable reactor in order that a simple, compact, and rugged overallstructure may be achieved.

A still further object of my invention is to provide a core arrangement for saturable reactors in push-pull magnetic amplier circuits which is particularly well adapted for a self contained or packaged construction.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, together with further objects and advantages thereof can best be understood by reference to the following description taken in connection with the accompanyingdrawing in which Fig. l. is a perspective view of the core structure and windings cf a saturable reactor in accord with my invention, Fig. 2 is a side sectional view of saturable reactor apparatus showing the saturaiole reactor of Fig. l assembled in a self-conor packaged form, Fig. 3 is a top plan view ci the apparatus of Fig. 2 with the cover removed and the various reactance and control windings emitted, and Figs, 4, 5, and 6 are schematic diagrams of magnetic amplifier circuits employing my invention illustrating the versatility of my invention as well as preferred internal connections of the reactor apparatus of Fig. 2 when in packaged form.

In general, my invention comprises an even plurality of at least four peripherally closed magnetic core elements which are preferably rectangular' in shape, and which are arranged in radial fashion such that one side portion or leg of each core element is contiguous a corresponding leg of each other core element to form a cen trai unified hub of a resulting star-shaped core arrangement. Each of a corresponding plurality of reactance windings are positioned on a respective outer leg of each core element, and one or more saturation control windings surround this central hub. A very convenient accommodation for current rectifying elements associated with the reactance windings is provided by the recesses between the windings of adjacent eX- tending core elements which result from this arrangement. Consequently, a sturdy and compact saturable reactor apparatus may be achieved when the components are assembled into a selfcontained package.

Referring to Fig. l, I have shown one embodiment of my invention as comprising a saturable reactor Ill having four peripherally closed centrally apertured core elements I I which are preferably quadrilateral and in the form of a hollow rectangle. The core elements II may conveniently be formed of U or L-shaped laminations stacked in a manner well known in the art. The core elements II are arranged in radially extending fashion with one side or leg of f each core element alongside a corresponding side or leg of each other core element so that an internal unified central core hub I2 is formed by the four mutually adjacent legs of the core elements.

At least one, and usually two or more magnetic saturation level control windings designated generally by numeral I3 are arranged to encircle the unified hub I2 of the core elements Il. rlhe turns of these control windings I3 pass through central apertures I4 provided in each of the core elements II in order to enable this encirclement ofthe central hub I2. One control winding, designated by the extending leads I5 and I functions as the signal receiving winding, while a second control winding, designated by the leads I1 and I8 may conveniently function as a feed back winding which may be connected to provide suitable regeneration or degeneration as a result of energy coupled back from a suitable load device (not shown). Additional control windings (not shown), such as a magnetic biasing winding to adjust the magnetic operating level of the reactor and means for mixing additional signals may, of course, also be included.

Four alternating current reactance windings I9 of the reactor are arranged on the respective outer sides or legs of the four core elements II, each passing though a corresponding aperture Ill of itsl associated core element alongside the cenl tral control windings I3.

A saturable reactor is thus provided in which the control windings I3 are arranged on a separate hub or leg I2 or" the reactor I0 and function to control the flux in symmetrical magnetic paths to respective ones of aplurality of alternating current reactance windings I9. In addition, the central hub I2 of the reactor constitutes a region of flux interaction for the magnetic flux produced by the respective currents flowing in the alternating current reactance windings IS. As will be more fully explained in connection with preferred circuit arrangements for the saturable reactor to be described below, this region of interaction functions when connected in pushpull circuits to produce a cancellation of reactance Winding flux in the central unified hub I2 of the reactor so that there is negligible alterna-ting current induced in the control windings I3.

The core elements II are preferably supported and rmly held together in this star-shaped arrangement by such means as four somewhat triangular non-magnetic base members 2i] which are secured together and to the core elements by such means as screws 2l which pass through suitable holes provided in the laminations of the core elements I I and are threaded into adjoining ones of the base members 2D. Similar upper nonmagnetic supporting members 22, best seen in Figs. 2 and 3, are wedged between the upper side portions of adjacent core elements II and are fastened together by such means as screws 23 in order to rigidly support the core elements II at the top.

It will be appreciated that with the abovedescribed star-shaped arrangement of the core elements Vand associated windings, a wedgeshaped space 24 is provided intermediate any pair of adjoining core elements II and between the upper and lower supporting members. This space 24 provides a very convenient accommodation for current rectifying elements, such as selenium or germanium rectifiers 25, which are commonly associated with the alternating current reactance windings of a, saturable reactor in magnetic amplier circuits. Consequently, this core arrangement lends itself `to the construction of a sel-fcontained or packaged saturable reactor apparatus which can conveniently be used in magnetic amplifier circuitry.

Referring now to Figs. 2 and 3, I have shown such packaged saturable reactor apparatus as it might be arranged in plug-in form. The saturable reactor I of l is secured upon a quadrilateral box-like spacing member 25' and secured to` the non-magnetic base members ZIJ of the reactor I0 by such means as screwsv 2l. Terminal means are provided such as a plug-in terminal 28 inserted within a circular aperture 25 in the bottom of the spacing member 21 and securely positioned by such means as a snap ring' 29. Suflicient space is provided between the top of the terminal 2B and the bottom of the saturable reactor base to accommodate the leads of the saturable reactor I0 and associated current rectifying elements 25 as they pass to connection (connections not shown) to the terminal connectors or prongs 30 of the terminal 2B.

In order to provide a support for the current rectifying elements 25 as well as to provide a convenient internal connection between the alnating current reactance windings I9 and associated current rectifying elements 25, four hollow rivets 3I are extended through the center of the upper supporting members 22. O-ne lead of each rectifying element 25 as well as one lead of an associated reactance winding I9 is inserted into the hollow center of each rivet 3 I. Suitable interconnection and support for these leads is accomplished by dropping molten solder into the center of the rivets 3|. The other leads of the rectifying elements 25, the control windings I3, and reactance windings I9 are passed through suitable holes 52 in the base members 20 of the reactor I0 and are connected (connections not shown) to suitable prongs 3B of the plug-in terminal 23.

The preferred internal connections for the saturable reactor apparatus shown in Fig. 2 as well as a fuller understanding of the magnetic relationship between the various windings of the reactor, can best be obtained by reference to the schematic diagrams of Figs. il, 5 and 6. Referring specifically to Figs. 4 and 5, I have shown the saturable reactor apparatus of Figs. l, 2 and 3 connected to serve as the controlling element in either a strict magnetic amplifier, as in Fig. 4, or as a "magnetic amplifying inverter, as in Fis. 5. In bot-h these Figs. 4 and 5, I have shown only Vone control winding although it is evident that additional control windings may be employed if desired. With one control winding only six terminals are necessary as shown. If, for example, two control windings are used, eight terminals would, of course, be needed.

In this preferred arrangement of Figs. 4 and 5, one pair of reactance windings, such as Windings I9a and IBb, are connected from respective output terminals 33 and 34 through separate reversely poled rectiers a and 25D to a common source voltage input terminal 35. The other pair of reactance windings Ic and 19d are connected in a similar manner through reversely poled rectiiiers 25e and 25d, from the output terminals 33 and 34 to a second source voltage input terminal 35. However, each pair of reactance windings I9 are connected or wound in reversed iiux relation with respect to the common control winding I3 in order that the saturating effect of the core elements II caused by the control winding I3 in one pair of the reactance windings, such as windings 19a and |9b, is in a direction opposite to the eifect produced upon the other pair of reactance windings ISC and 19d.

In the external circuit of Fig. 4, shown in light lines, a load device 3l' is connected between the output terminals 33 and 34, and a pair of substantially identical impedances 38 and 39 are respectively connected in parallel from each output terminal 33 and 34 to one side of an alternating voltage source 4I] whose other side is connected to both input terminals 35 and 3S. This circuit of Fig. 4 operates, with a positive signal on the control winding I3, to hasten the saturation of one pair of reactance windings, such as windings IBa and Itb, while it retards the staturation of the other pair of reactance windings 13o and ISd. Due to the reversely poled rectii'iers 25 in series with each reactance winding I9 and to the crossed connection to the output terminals 33 and 34, it will be seen that voltage difference between the output terminals 33 and 34 is developed by unequal currents flowing through the impedances 38 and 39, and that this voltage diiference will always be in the same direction for a given polarity of control winding signal. Consequently, the current through the load device 31 follows the variations in the signal voltage supplied to the control windings I3.

Referring now to Fig. 5, I have shown the identical saturable reactor apparatus of Fig. 4 as it might be connected in a diiferent external circuit to form an amplifying magnetic inverter instead of a strict magnetic amplier as in Fig. 4.

In this circuit, the load 31 is connected between t.

the terminals 35 and 33 that constituted the source voltage input terminals of the magnetic amplier of Fig. 4. The pair of substantially identical iinpedances 38 and 39 are connected in parallel from each of these terminals 35 and 36 to one side of the alternating voltage source 4l] whose other side is connected to both of the terminals 33 and 34 which constituted the output terminals of Fig. 4. When connected in this manner, the current in the load device 31, with a signal of given polarity supplied to the control windings I3, is dependent upon the difference in voltage at the terminals 35 and 33 produced by unequal currents flowing in the iinpedances 33 and 3S as a result of the oppositely directed c saturation effect on each pair of reactance windings IQ. However, the preponderance of voltage shifts from one of the terminals 35 and 33 to the other thereof together with the alternations in polarity of the source voltage. Consequently, an

alternating current iiows through load device 31 when a unidirectional signal voltage is supplied to control winding I3, and the magnitude and sense of this alternating current depends upon 'the amplitude and polarity of the unidirectional voltage signal. Conversely, with an alternating current signal derived from an alternating voltyage source 40 supplied to control winding i3, a

unidirectional current iiows through load 31 whose polarity is dependent upon the phase of this alternating current signal relative to the -phase of the alternating voltage source 4I); and

whose amplitude varies in accordance with the magnitude of the alternating current signal.

The above circuits shown in Figs. 4 and 5, form the subject matter and are fully described and claimed in a copending application Serial Number 169,847 of Raymond E. Morgan entitled Electric Control Circuits Using Saturable Reactors led concurrently with the present application and assigned to the same assignee as the present invention.

Referring to Fig. 6, I have shown an alternative manner of connecting the saturable reactor apparatus of Figs. 2 and 3. In this circuit, the reactance windings I9 of each pair are connected to opposite source voltage input terminals 35 and 36 and the series connected current rectifying elements 25 are all similarly poled; one pair of reactance windings 19a and 19h being connected through current rectifying elements 25a and 25h to the same output terminal 33, and the other pair of reactance windings |30 and i3d being connected through the other pair of similarly poled rectiers 25C and 25d, to the other output terminal 34. In this circuit, I have also shown two control windings I3a and I3b brought out to appropriate terminals. The saturable reactor apparatus of Fig. 6 is, therefore, identical with that of Figs. 4 and 5 with the exception that the rectifying elements 25 are similarly poled and the connections to the respective input and output terminals reversed. One pair of reactance windings such as windings 19a and I9b are reversely wound with respect to the other pair of reactance windings I9c and 19d in order that a signal supplied to the control winding 13a will have oppositely directed saturation effect upon each pair of reactance windings. The magnetic interaction of the iiux in the core is, therefore, identical with that of the circuit shown in Figs. 4 and 5. The external circuit of Fig. 6 constitutes a conventional push-pull amplifier circuit in which a center-tapped transformer 4I is connected to supply current to the input terminals 35 and 36, and a pair of substantially identical impedances 33 and 33 are respectively connected between the center tap of the transformer and each output terminal 33 and 34 of the saturable reactor apparatus. A suitable load device 31 is connected between the output terminals 33 and 34 and the feed back control Winding 13b is connected across this load device 31. The detailed operation of this circuit is well known to those skilled in the art and need not be described here.

It will be appreciated that if the reactance windings lila and IBb and the reactance Windings 19e and 13d were wound on the cores of separate reactors, there would be no interaction between the iiux produced in one reactor by the currents flowing through windings I9a and IQb and the iiux produced in the other reactor by currents iiowing through the other pair of reactance windings ISC and I9d. Since current would ilow in` an'oppositedirection in each reactance winding of each of these separate reactors during alternate half cycles of source voltage, an alternat-ing current would normally be induced in the separate control windings associated with these separate reactors by the reveresal of flux in the. core. However, by combining the two reactors into a single unified structure in accordance with my invention, there is a cancellation oi oppositely directed magnetic flux produced in the central uned hub or leg l2 of my saturable reactor l0 bvA simultaneous currents owing in the reversely connected pairs of reactance windings lila, IBb and l9c, |921 during both alternations of source Voltage. For example, when connected in the push-pull circuits of Figs. 4, and 6, the flux produced in hub l2 by the core element associated with reactance winding Hic is cancelled by the ux produced in hub l2 by the core element of reactance winding 29C during source voltagealternations of one given polarity, both reactance windings I9a and 19o being conductive during the same half cycle of source voltage. A similar cancellation of uX in the central hub l2 is produced by the simultaneous currents in reversely connected reactance windings l9b and Id during source voltage alternations of opposite polarity. As a result, there is little or no alternating voltage induced in the control windings i3 which surround this central hub l2.

It will thus be seen that I have provided a compact and sturdy saturable reactor apparatusi which is very well adapted for use in push-pull magnetic ampliiier circuits. The star-shaped arrangement of the core not onlyprovides improved performance due to the magnetic interaction oi the flux produced by the respective alternating current windings on the outer legs of the'various core members, but also enables a convenient location for the current rectifying elements associate-d with these reactance windings. In addition, the entire arrangement provides a compact self-contained saturable reactor apparatus which can be adapted to many different magnetic amplier circuits.

It will be understood that although I have shown particular embodiments of my invention, many other modications will occur to those skilled in the art. It is evident, that this same star-shaped core structure may )be employed whenever it is desired to control the current through four or more reactance windings by the same electric signal. When employed in threephase push-pull alternating current circuits, for example, six core elements, may be radially arranged into a unied reactor in accord with my above-described invention. I intend, therefore, by they appended claims to cover all such modifications as fall within the true scope and spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Saturable reactor apparatus comprising an even number of at least four similar peripherally closed centrally apertured magnetically saturable core elements extending radially with one side portion of each element alongside a corresponding side portion of each other element to form a central unified hub, at least one magnetic saturation control winding passing through the central aperture of each core element and encircling said hub, a separate alternating current reactance winding encircling an opposite side portion of each core element, and a corresponding number of current rectifying elements located in a space intermediate the windings associatedwith adjoining core elements, each current rec-- tifying element being connected to an adjacent one of said reactance windings and being polarized relative to the other rectiers to enable simultaneous conduction through said rectiers in respective pairs of reactance windings, each simultaneously conducting reactance winding of each pair being arranged on its core to produce oppositely directed iiux in said hub relative to the other simultaneously conducting winding thereof.

2. saturable reactor apparatus comprising a plurality of terminal connectors, an even number of at least four quadrilateral centrally apertured magnetically saturable core elements extending radially with one side portion of each element alongside a corresponding side portion of each other element to form a central unified hub in a star-shaped core arrangement, a magnetic saturation control winding passing through the central aperture of each core element to encircle said hub and connected across one pair of said terminal connectors, a separate alternating current reactance winding encircling an opposite side portion of each core element, and a corresponding number of current rectifying elements each located in a space intermediate the windings associated with adjoining core elements, each of said reactance windings being connected in series with an adjacent associated current rectifying element between preselected other ones of said terminal connectors said rectifying elements being relatively polarized to enable simultaneous conduction through said rectiiers in respective pairs of reactance windings, each simultaneously conducting reactance winding of each pair being arranged on its core to produce oppositely directed ux in said hub relative to the other simultaneously conducting winding thereof.

3. saturable reactor apparatus adapted for use with push-pull magnetic amplier circuits comprising four similar rectangular magnetically saturable core elements each having a central aperture and arranged in radial fashion with one side portion of each element alongside a corresponding side portion of each other element to form a central hub within a star-shaped unified core structure, at least one magnetic saturation control winding passing through the central aperture of each core element and encircling said hub, four alternating current reactance windings each encircling an opposite side portion of a respective one of said core elements, and four current rectifiers each located in a space intermediate the windings associated with adjoining core elements, each current rectiiier` being connected to an adjacent one of said reactance windings and being polarized relative to the other rectiers to enable simultaneous conduction in respective pairs of reactance windings upon the application of an alternating voltage across said reactance windings through said rectiiiers, and the reactance windings of each pair of simultaneously conducting windings being arranged on their respective cores to produce a mutual flux opposition in said hub.

4. Saturable reactor apparatus comprising terminal means having three pairs of terminal connectors, four similar quadrilateral centrally apertured magnetically saturable core elements extending radially `with one side portion of each core element alongside a corresponding side portion of each other core element to form a centrol uniiied hub within a star-shaped core structure, a magnetic saturation control winding passing through the central aperture of each core element to encircle said hub and connected across a rst pair of said terminal connectors, four alternating current reactance windings each encircling an outer side portion of a respective one of said core elements, and four current rectifying elements each located in a space between the reactance windings of adjoining core elements, each reactance winding being connected in series with a respective one of said current rectifying elements from preselected ones of a second pair of said terminal connectors to preselected ones of the third pair of said terminal connectors said rectifying elements being relatively polarized to enable simultaneous conduction in respective pairs of the four reactance windings when alternating voltages are applied between said second and third pairs of terminal connectors, and each reactance winding of each simultaneously conducting pair being arranged on its core to produce iiux in said hub opposing the iiux produced therein by the other.

5. A saturable reactor apparatus comprising a pair of input terminals and a pair of signal receiving terminals, four rectangular centrally apertured magnetically saturable core elements extending radially with one side portion thereof alongside a corresponding side portion of each other core element to form a central inner unified hub in a star-shaped core arrangement, a magnetic saturation control winding connected across said signal receiving terminal and passing through the central aperture of each core element to encircle said hub, a separate alternating current reactance winding encircling the outer side portion of each core element and four current rectifiers each located in a space provided intermediate the windings associated, with adjoining core elements, one pair of said reactance windings being connected in series with reversely poled ones oi said rectiers from the same one of said input terminals to respective ones of said output terminals, and the other pair of said reactance windings being connected in series with reversely poled other ones of said current rectiiiers from the other one of said input terminals to respective ones of said output terminals.

6. A saturable reactor apparatus comprising a pair of input terminals, a pair of output terminals and a pair of signal receiving terminals, four rectangular centrally apertured magnetically saturable core elements extending in radial fashion with one side portion thereof alongside a corresponding side portion of each other core element to form a central inner unified hub in a star-shaped core arrangement, a magnetic saturation control winding connected across said signal receiving terminal and passing through the central aperture of each core element to encircle said hub, a separate alternating current reactance winding encircling the outer side portion of each core element, and four current rectiflers each located in a space intermediate the windings associated with adjoining coreV elements, one pair of said reactance windings being connected in series with similarly poled ones of said rectiiiers from the same one of said input terminals to respective ones of said output terminals, and the other pair of said reactance windings being connected in series with similarly poled other ones of said current rectiiiers from the other one of said input terminals to respective ones of said output terminals.

HUGH M. OGLE.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 1,157,730 Spinelli Oct. 26, 1915 1,910,381 Dowling May 23, 1933 2,509,738 Lord May 30, 1950 2,509,864 Hedstrom May 30, 1950 FOREIGN PATENTS Number Country Date 589,341 Great Britain June 18, 1947 

